Magnetic compass compensating device



932. G. L. J. MARTIN 1,881,207

MAGNETIC COMPASS COMPENSATING DEVICE Filed July 9, 1928 Z SheetS-Sheet 1 Oct. 4, 1932. J, MARTlN 1,881,207

MAGNETIC COMPASS COMPENSATING DEVICE Filed July 9, 1928 2 Sheets-Sheet 2 Patented Oct. 4, 1932 UNITED STATES PATENT OFFICE MENTS AERA, OF PARIS, FRANCE MAGNETIC CbMPASS COMPENSATING DEVICE dlpplication filed. July 9, 1928, Serial No. 291,393, and in France July 12, 1927.

"With certain devices at present in use for magnetic compasses, varlation of the compensating effect is obtained by varying the displacement or even by removal of the compensators. Said devices are cumbersome, canof the compass card.

not be adjusted to zero and necessitate removable and interchangeable irons or magnets.

I 7 Other semi-circular compensating arrange ments contemplate the possibility of opposing the magnets; annulling is then possible but requires a great number of magnets and its maintenance is dependent on the stability of magnetization of the. correctors.

V The object of the invention is to provide compensating devices in which the suppression mentioned above is obtained by a par- '20 ticular positioning of each of the irons or compensating magnets, such positioning being geometrically determined and independent ofthe value of the magnetization of the correctors and not necessarily dependent upon opposite arrangements of pairs of the latter; adjustment of the correctors being effected by appropriate devices operating in a manner to dispose or position the irons or magnets at one side or the other and in one or more planes, stationary and parallel to the plane In the accompanying drawings and in the description which is to follow, there are set forth different embodiments of the invention and, in th drawings Figure 1 is a diagrammatic view of a compensatingdevice embodying the invention and of a semi-circular'type;

Figs. 2and 3 are diagrammatic views illus: trating'the elementary arrangement of two magnets whereby the relative arrangements that are to be made by their symmetric adj ustment in unison with each other will afford a very accurate suppression of the compensating coupl in all azimuths;

Figs. 4: to 7 are: plan views illustrating several possible arrangements or groupings of the correctors; j

Figs. 8 and 9 are plan views partly in section illustrating other embodiments of the invention;

Figs. 1, 2 and 3 illustrate, diagrammatically, an embodiment of the invention which I mark the non action point A corresponding to an angle 0c of the magnet l with respect to the radius concerned. All points in the plane corresponding to angle a are on a curve Goa. If the value of on is suitably selected,said curve will very substantially be a circle 0 havcingR as a radius and concentric with the car If the magnetis secured on a support connected with the binnacle in the position thus defined, the compensating torque will be substantially nil for any azimuth. So, in the case of a card having one magnet 2a in length and of a single small compensator magnet:

oc=0, 13 0, 7a

m In point of fact, an arrangement so simple does not permit of an absolutely nil effect being ensured for any azimuth. But, instead of having a single magnet, I may provide a plurality of magnets in suitably arranged groups, the position of each of said magnets, defined by angle a and radius B, being fitted to the general configuration of the whole compensating device and, of course, to the design of the mobilegear.

Figures 2 and 3 show elementary arrangements of two magnets 1, each of which arrangements may be determined by means of their symmetry and combined with one another so as to afl ord a very accurate annulling of the compensating torque in any azimuth.

' Adjustment as to direction and as to intensity of said torque is obtained by moving LOUIS JULES MART IN, 0F COURBEVOIE, FRANCE, ASSIGNOR T0 ETABLISSE- the whole or part of the elements of the corrector assemblage in one or more fixed planes parallel to the plane of the card relative to the positions ofnon-action above defined The compensator torque. thus obtained is a function very perceptibly semi-circular of the azimuth and is the closer to it the more the selected arrangement gives, in its zero position, anaccurate annuling of the torque in any azimuth.

" Adjustment as to direction determined it by utilizing, in the wellknown manner, two sets connected with the binnacle and having respectively their maximum efiect'in two rectang ula'r directions. which are generally the one parallel to the axis of theairship and the other perpendicular to said axis. ?Action is exerted ontheop'erative intensities or these two sets so as to achieve'a compensator resultant adjustableboth as to magnitude and as todirection.

From the foregoing it is evidently possible to replaceeach element by a nest of magnets,

. J .7 arranged parallel or not, ands'o associated as 25 to permit of their power being varied or con servation of said power ensured. I In Figures 4v to 7 inclusive, the magnets 1 are mounted on supports 2 so arranged as to be 'slidable along slides 3. Supports 2 are controlled by means of a screw 4 provided with" alknurled plug 5 and'longitudinally.

blocked by bearings 6 integral with plate 7. In said Figures 4 and 7 the screw 4 is a right and left hand one so that themotions of the two groups of magnets will: bejsymmetrical.

With the arrangements illustrated by Figures 5 and 6 there is but one movable group and the screw is. single threaded. For symmetry, there could be, a'djoined to those far- .rangements a stationary group similar to'the latingsolely to one of the components of the 'justing screw with rightand left-hand threads, theunits or parts of the assemblage distributor field. Figs. 4 and 7 illustrate an arrangement whereby, by the use of an adof-magnetic correctors may be adjusted simult-aneously and equally, while thearrangements shown in Figs. 5 and 6 illustrate forms in which adjustment of only one unit .is required'to be made.

The quadrantal compensation device best shown in Fig. 8 and is based on the employment of'soft irons 11 of Suitable mass and shape, positioned in a plane parallel to I the card and the operative intensity of which 7 E parallel to axis Z-Z" without removing is adjustable throughadjustingitheir'spacing them from their plane. Suppression of the quadrantal corrector eflect is' obtained through juxtaposition of said irons. The half-ring shape is particularly convenient since the two juxtapositioned irons then form a substantially complete symmetrical ringwhich, obviously, can have no action onthe card in any azimuth. Inor'der to further increase said symmetry, there can be provided between the two half-ringstwo stationary air-gaps 0 e perpendicular to the variable air-gaps E and intended magnetically to balance them in zero position.

As stated above, thezinvention contemplates giving to the soft iron bodies a suitable form,-so that when-they are adjusted with respect to each-otherf i t, direction at right angles to the axis of'thecompassfln a common plane'abovethe card of the compass, they constitute .an assemblage without'action on the same. Thus, while the compensation for quadrantal deviation may be feeble, it

may be made without the necessityof sepa rating thejsoft iron 'bodiesvery far :trom each other or removing them, while all the time preserving the possibility of compensating for a substantial deviations The extent of adjustment is regulatedby varying the separation of the iron bodies by-a' double movementin a-plane perpendicular to the giving-to the-semi-annular bodies a-true semis circular form, they may be given a form approximating a square or "an octagon if there he need for octantal 'cOrrectionr The invention also contemplates another type of compensation, namely the octantal which is obtained by giving tothe half-rings a shape approximating a square or an octagon so as to obtain, if need be, an octantal cor rection as distinguished from the quadrantal correction above described. 1

In both cases, adjustinentias to intensity is efi'ected by varyingthe size of the air-gaps E, and adjustment as to; direction efiected by causing the set to be revolvedround the axis of the card by means of, a suitable dee vice.v

Such an arrangement may be. embodied as illustrated, for example in Figure 9.,

In this embodiment, iron bodies 17, mounted' on supports 12, are slidable alongafslide' 13 and are controlled. by' a. screw. .14 with rightand left-hand threads.- .[The set is mountedon a plate 8 rota-table round theaxis of thecompass, as, for example, byimeans of a screw 9 tangential with respect to and meshing with a circular rack integral with plate 8.

It is to be clearly understood that the above described embodiments are not intended as in any Way limitative and may be modified in any desirable manner without departing from the scope of my invention.

Having now particularly ascertained and described the nature of my said invention V as well as the manner in which the same is to r J presslon of the usual compensatlng effect,

he performed, I declare that what I claim is:

- 1. A magnetic compass compensating device, comprising, in combination with the card of the compass, means for effecting supsuch means comprising compensating iron bodies of substantially semi-annular form 1 mounted at opposite sides of the axis of the bodies around said compass axis in a plane parallel to the card of the compass; the inner sides of the iron bodies being semi-circular and the outer sides being of angular form to provide for polygonal compensation.

In testimony whereof I affix my signature. GEORGES LOUIS JULES MARTIN. 

